Simulation Study On The Transient Process Of High-Voltage Current-Limiting Fuse

High-voltage current-limiting fuse has low price and it can cut off the short circuit current more rapidly than breaker, so it is used to protect the generator,transformer and other electrical equipments in power system. At the mean time of the high-voltage current-limiting fuse cutting off the current, the fuse will melt and boil away, and it will generate electric arc with high temperature and high pressure. During the arcing time there is high arc voltage with huge energy which could damage other facility in the circuit. This paper analyze the transient of the high-voltage current-limiting fuse based on the short circuit test system. The results of the research can be used as the principle to select fuse and solve the protection problem of thermal effect and overvoltage.The essence of the transient of the high-voltage current-limiting fuse cutting off the current is a complicated arcing process. The arc resistance changes from small value to big value nonlinearly, the fuse transfers from conductor to insulator. In the whole transient process the fuse goes through solid state,liquid state and gaseous state.The paper analyze the current field and temperature field of the fuse during the transient process and link the two fields above based on energy conservation law. A model of the thermoelectric coupling field of the fuse is established. Considering the phase state changing of the high-voltage current-limiting fuse during transient process, we built a normal fore-arc fuse model and arc fuse model. The arc fuse model is a increase simplified cylinder model which can describe the whole arcing process. To solve the model the finite element method is adopted based on ANSYS. By setting up the boundary condition,initial condition and loading the current, we simulated the entire transient process of the high-voltage current-limiting fuse using ANSYS. The fore-arc time-current character and nonlinear resistance-time character of the high-voltage current-limiting fuse is obtained. It will give help to calculate the other parameters of the high-voltage current-limiting fuse transient process.Finally the paper built the mathematic model of the short circuit test system of the high-voltage current-limiting fuse. In this model the fuse is simulated by a time variable nonlinear resistor. By simulating the fusing process, the overvoltage during the arc time,current-limiting character,I 2 t and current changing of the fuse is acquired. With all the parameters above we could describe the transient process exactly.